The Thunderbox pro can hold two 18650 batteries improving maximum power output and battery life. The maximum power is up to 160W. This would be perfect for those who are dabbing consistently throughout the day because it won't die as fast. It is recommended to be used with the Bolt M Pro.
On the other hand, the Thunderbox, only holds one 18650 battery and does allow adjustable overtime protection up to 20 seconds. The maximum power is up to 80 Watts. This is perfect for those people who only dab a couple times through out the day and if you want a super portable box mod. It is recommended to be used with the Bolt M.